IDC estimates Linux will have 7% of the desktop market in 2008, up from 3% now. This makes it a "mainstream" operating system, according to IDC.

So does that mean the Macintosh isn't? IDC doesn't say. IDC doesn't have to.

IDC previously estimated the 2008 Linux server market at $9 billion, and now has Linux with $11 billion in servers, and another $10 billion in PCs. In this study the total Linux "ecosystem" market grows almost 26% per year, to $35.7 billion in 2008.

Your mileage will vary, of course. These are guesses, estimates, extrapolations, what I like to call "hockey sticks" because that's what the numbers, when graphed, usually look like. Time, in other words, will tell.

But my question is this. If Linux were a stock, would you buy it? Especially in comparison to that of Apple, whose price-earnings ratio was last sighted somewhere north of 90?